The United States’ government has explained why it is opposed to the selection of former Nigerian finance minister, Ngozi Okonjo-Iweala, as the director-general of the World Trade Organisation (WTO).

The U.S. made its position known late Wednesday in a statement by the Office of the US trade representative on the WTO director-general selection process.

The United States said it supported the selection of Korean Trade Minister Yoo Myung-hee as the next WTO Director-General because she is “a bona fide trade expert who has distinguished herself during a 25-year career as a successful trade negotiator and trade policy maker.”

The statement said the minister has all the skills necessary to be an effective leader of the organisation.

“This is a very difficult time for the WTO and international trade,” the statement said.

“There have been no multilateral tariff negotiations in 25 years, the dispute settlement system has gotten out of control, and too few members fulfill basic transparency obligations.”

Although the U.S. did not mention Okonjo-Iweala, it however said that “The WTO is badly in need of major reform. It must be led by someone with real, hands-on experience in the field.”

Okonjo-Iweala’s ambition suffered a setback as the United States failed to endorse her for the top job.

The former Nigerian minister had moved a step closer to becoming the first woman and the first African to be the director of the global trade watchdog as she secured the support of a key group of trade ambassadors in Geneva.

But the U.S. raised last-minute objections to the process by which the new director general was being picked.

A spokesperson for the WTO on Wednesday said Okonjo-Iweala’s candidacy would be put to a meeting of the body’s governing general council on November 9.

The role became available because of the unexpected early resignation of Roberto Azevêdo, a Brazilian who had held the job since 2013. He had another year remaining in his term of office but stepped down in September.

The organisation is currently without an interim director-general after China vetoed a US suggestion that the American Alan Wolff, one of the deputy directors-general, should take over in an acting capacity.